Warsaw - under whose occupation in late 19th century?

A question to the historians and history buffs on PF.... I believe Warsaw was in the Prusuian partition zone and in 1918 Poles in Warsaw disarmed German soldiers (who afctually let themselves be disarmed). That all makes sense. However, why were all the shop signs in Wokulski's Warsaw in Polish and Russian? Did a border shift occur between the partitioning pwoers at that time?

how many troops the Soviet had in Poland Harry? and how many NKVD or KGB agents?

The Polish army was infiltrated by Soviet citizens which spoke poor Polish (maybe they had some Polish background from their tip tip tip grandfather but, that doesn't help much... Look at Putin he had a Polish grandmother... He is still Russian)